1. Field of the Invention
The invention relates to a process for the preparation of light-colored oleic acid sulfonates.
2. Description of Related Art
The preparation of oleic acid sulfonates by reaction of industrial oleic acid cuts with gaseous sulfur trioxide is known from GB-C 1,278,421. This publication makes the following statements on the color of the oleic acid sulfonates obtained by this process: 1. The color of the sulfonation products depends on the reaction conditions, in particular the contact time in the reactor and the temperature of the starting substances fed to the reactor. 2. The color of the sulfonation products depends on the amount of sulfur trioxide employed, an excess of more than 15 mol %, based on oleic acid, resulting in poorer colors with only a slight increase in the degree of conversion. 3. The color of the sulfonation products depends on the content of polyunsaturated fatty acids in the industrial oleic acid employed, a content of more than 3% of these polyunsaturated fatty acids leading to poor colors of the sulfonation products.
There are available on the market numerous industrial oleic acid grades, in particular those of regenerating naturally occurring raw materials, such as beef tallow, lard, olive oil, sunflower oil and palmkernel oil, which have contents of polyunsaturated fatty acids of more than 3% and to date could not be sulfonated by the process known from GB-PC 1,278,421 to form light-colored oleic acid sulfonates.